Mask and method for delivering a therapeutic breathable substance

ABSTRACT

A mask may be used in therapeutic gas delivery to one or more external orifices (e.g., the nostrils and/or mouth) of a subject in accordance with an embodiment of the present invention. The mask may include a mask body, a seal portion, a source connector, and an exhaust valve. The mask may be configured to be placed against the face of the subject  12  with a sealed interface therebetween such that a chamber is formed by the mask and the face of the subject that encloses the one or more external orifices of the subject. During use, a breathable substance can be provided into the chamber from a source of the breathable substance through the source connector.

This patent application claims the priority benefit under 35 U.S.C.§119(e) of U.S. Provisional Application No. 61/141,253 filed on Dec. 30,2008, the contents of which are herein incorporated by reference.

This application is related to U.S. patent application Ser. No. ______,61/141,254 filed Dec. 30, 2008, which is hereby incorporated into thisapplication in its entirety.

The invention relates to the delivery of a therapeutic breathablesubstance to the airway of a subject.

Conventional nebulizers, spacers, and other therapeutic gas deliverymechanisms implement masks that enclose the nostrils and/or mouth of asubject for delivery of a breathable substance. Generally, these masksinclude exhaust valves for exhausting gas exhaled by the subject toatmosphere. These valves are typically formed on the body of the mask,which may impede a view of the nose and/or mouth of the subject throughthe mask for a caregiver monitoring the therapy. Conventional masks maynot provide an adequate indicator to the monitoring caregiver of whetheror not the subject has exhaled. This may be important for therapies thatare dosed in terms of breaths.

One aspect of the invention relates to a mask for substantially sealingthe airway of a subject for delivery of a breathable substance. In oneembodiment, the mask comprises a mask body, a source connector, a maskseal portion, and a one-way valve. The mask body is configured toenclose one or more external orifices of the airway of a subject, andforms a substance opening through which a breathable substance can becommunicated to the one or more external orifices of the subject thatare enclosed by the mask body. The source connector is disposed on themask body, and comprises a conduit that forms a gas flow path betweenthe substance opening of the mask body and a source interface openingformed in the source connector. The source connector is configured toconnect a source of the breathable substance to the gas flow pathbetween the substance opening of the mask body and the source interfaceopening. The mask seal portion is attached to the mask body, and isconfigured to provide a substantially sealed engagement between the faceof the subject and the mask body around the one or more externalorifices of the airway of the subject. The one-way valve is disposed onthe source connector, and is configured to permit gas within the gasflow path formed by the source connector to be exhausted to ambientatmosphere and to substantially seal the gas flow path from inflows ofambient atmosphere.

Another aspect of the invention relates to a mask for substantiallysealing the airway of a subject for delivery of a breathable substance.In one embodiment, the mask comprises means for forming a chamber thatencloses one or more external orifices of the airway of a subject,wherein a portion of the chamber is formed by the face of the subject;means for placing a source of a breathable substance in communicationwith the chamber via a conduit forming a gas flow path between a sourceinterface opening and a substance opening formed in the chamber byconnecting the source of the breathable substance to the sourceinterface opening; means for delivering the breathable substance fromthe source of the breathable substance to the chamber through theconduit without permitting inflows from ambient atmosphere into theconduit; and means for exhausting gas exhaled by the subject to ambientatmosphere through an exhaust opening in the conduit.

Another aspect of the invention relates to a method of substantiallysealing the airway of a subject for delivery of a breathable substance.In one embodiment, the method comprises forming a chamber that enclosesone or more external orifices of the airway of a subject, wherein aportion of the chamber is formed by the face of the subject; placing asource of a breathable substance in communication with the chamber via aconduit forming a gas flow path between a source interface opening and asubstance opening formed in the chamber by connecting the source of thebreathable substance to the source interface opening; delivering thebreathable substance from the source of the breathable substance to thechamber through the conduit without permitting inflows from ambientatmosphere into the conduit; and exhausting gas exhaled by the subjectto ambient atmosphere through an exhaust opening in the conduit.

Another aspect of the invention relates to a mask for substantiallysealing the airway of a subject for delivery of a breathable substance.In one embodiment, the mask comprises a mask body, one or more exhaustopenings formed in the mask body, a first valve member, and a secondvalve member. The mask body is configured to enclose one or moreexternal orifices of the airway of a subject such that the mask body andthe face of the subject form a chamber around the one or more externalorifices of the airway of the subject that are enclosed by the maskbody. The mask body further includes a source connector configured toconnect a source of a breathable substance with the chamber such that aflow of the breathable substance is provided from the source to thechamber through the source connector. The one or more exhaust openingsformed in the mask body exhaust gas within the chamber to ambientatmosphere. The first valve member covers a portion of the one or moreexhaust openings to block inflows of gas at ambient atmosphere fromentering the chamber via the one or more exhaust openings. The firstvalve member is configured such that exhalation of gas from the one ormore external orifices of the airway of the subject applies a force thatactuates the first valve member to uncover the portion of the one ormore exhaust openings covered by the first valve member in order toexhaust the exhaled gas if the pressure of exhaled gas within thechamber is equal to or greater than a first pressure. The second valvemember covers a portion of the one or more exhaust openings to blockinflows of gas at ambient atmosphere from entering the chamber via theone or more exhaust openings, and is configured such that exhalation ofgas from the one or more external orifices of the airway of the subjectapplies a force that actuates the second valve member to uncover theportion of the one or more exhaust openings covered by the second valvemember if the pressure of exhaled gas within the chamber is equal to orgreater than a second pressure. The first pressure is less than thesecond pressure such that actuation of the first valve member by exhaledgas provides an indicator to a caregiver of relatively weak exhalationsby the subject and actuation of the second valve member by exhaled gasoccurs in combination with actuation of the first valve member duringstronger exhalations by the subject to reduce the resistance to gas flowthrough the on or more exhaust openings during relatively strongexhalations.

Another aspect of the invention relates to a method for substantiallysealing the airway of a subject for delivery of a breathable substance.In one embodiment, the method comprises forming a chamber that enclosesone or more external orifices of the airway of a subject, wherein aportion of the chamber is formed by the face of the subject; blockinginflows of gas at ambient atmosphere from entering the chamber via oneor more exhaust openings, wherein the one or more exhaust openings areblocked at least in part by a first valve member that covers a portionof the one or more exhaust openings and a second valve member thatcovers a portion of the one or more exhaust openings; at or above afirst pressure within the chamber, uncovering the portion of the one ormore exhaust openings covered by the first valve member to release gaswithin the chamber to atmosphere; at or above a second pressure withinthe chamber, uncovering the portion of the one or more exhaust openingscovered by the second valve member to release gas within the chamber toatmosphere; wherein the first pressure is less than the second pressuresuch that the uncovering of the portion of the one or more exhaustopenings covered by the first valve member to release exhaled gas toatmosphere provides an indicator to a caregiver of relatively weakexhalations by the subject and the uncovering of the portion of the oneor more exhaust openings covered by the second valve member to releaseexhaled gas occurs in combination with the uncovering of the portion ofthe one or more exhaust openings covered by the first valve memberduring stronger exhalations by the subject to reduce the resistance togas flow through the on or more exhaust openings during relativelystrong exhalations.

Another aspect of the invention relates to a mask configured tosubstantially seal the airway of a subject for delivery of a breathablesubstance. In one embodiment the mask comprises means for forming achamber that encloses one or more external orifices of the airway of asubject, wherein a portion of the chamber is formed by the face of thesubject; means for blocking inflows of gas at ambient atmosphere fromentering the chamber via one or more exhaust openings, wherein the meansfor blocking comprise a first valve member that covers a portion of theone or more exhaust openings and a second valve member that covers aportion of the one or more exhaust openings; means for, at or above afirst pressure within the chamber, uncovering the portion of the one ormore exhaust openings covered by the first valve member to release gaswithin the chamber to atmosphere; means for, at or above a secondpressure within the chamber, uncovering the portion of the one or moreexhaust openings covered by the second valve member to release gaswithin the chamber to atmosphere; wherein the first pressure is lessthan the second pressure such that the uncovering of the portion of theone or more exhaust openings covered by the first valve member torelease exhaled gas to atmosphere provides an indicator to a caregiverof relatively weak exhalations by the subject and the uncovering of theportion of the one or more exhaust openings covered by the second valvemember to release exhaled gas occurs in combination with the uncoveringof the portion of the one or more exhaust openings covered by the firstvalve member during stronger exhalations by the subject to reduce theresistance to gas flow through the on or more exhaust openings duringrelatively strong exhalations.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. In one embodiment of the invention, the structuralcomponents illustrated herein are drawn to scale. It is to be expresslyunderstood, however, that the drawings are for the purpose ofillustration and description only and are not a limitation of theinvention. In addition, it should be appreciated that structuralfeatures shown or described in any one embodiment herein can be used inother embodiments as well. As used in the specification and in theclaims, the singular form of “a”, “an”, and “the” include pluralreferents unless the context clearly dictates otherwise.

FIG. 1 illustrates a mask 10 for use in therapeutic gas delivery, inaccordance with one or more embodiments of the invention.

FIG. 2 illustrates a mask 10 for use in therapeutic gas delivery, inaccordance with one or more embodiments of the invention.

FIG. 3 illustrates a mask 10 for use in therapeutic gas delivery, inaccordance with one or more embodiments of the invention.

FIG. 4 illustrates a mask 10 for use in therapeutic gas delivery, inaccordance with one or more embodiments of the invention.

FIG. 5 illustrates a method of isolating the airway of a subject fromatmosphere to facilitate delivery of a breathable substance, accordingto one or more embodiments of the invention.

FIG. 1 illustrates a mask 10 for use in therapeutic gas delivery to oneor more external orifices (e.g., the nostrils and/or mouth) of a subject12 in accordance with an embodiment of the present invention. The mask10 may generally include a mask body 14, a seal portion 16, a sourceconnector 18, and an exhaust valve 20. The mask 10 is configured to beplaced against the face 22 of subject 12 with a substantially sealedinterface therebetween such that a chamber 24 is formed by mask 10 andthe face of subject 12 that encloses the one or more external orificesof subject 12. During use, a breathable substance can be provided intochamber 24 from a source (not shown) of the breathable substance throughsource connector 18.

Mask body 14, in one embodiment, is made of a relatively more rigidmaterial (higher durometer material) than seal portion 16. For example,mask body 14 may be made from polycarbonate, or other suitable material.The mask body 14 provides structural rigidity to the mask 10 and, insome embodiments, may be a portion of a disposable mask that is retainedwhen replacing the seal portion 16. The mask body 14/seal portionstructure may be formed by a two-step molding or assembly process. Forexample, the relatively harder mask body 14 may be molded first and theninserted into a second mold for the seal portion 16, which is injectionmolded to form around and/or into the mask body 14. In one embodiment,mask body 14 and seal portion 16 are of a similar durometer (e.g., lessrigid), and/or may be formed as a single piece.

Seal portion 16 may be made of a relatively soft and/or flexiblematerial so that the seal portion 16 conforms to the shape of the face22 of subject 12 when held against it. Seal portion 16 may be made of,for example, silicone or an elastomeric material. In one embodiment,seal portion 16 has an arcuate or partially tubular cross-sectionalconfiguration (also referred to as a concavo-convex cross-section,having a generally concave inner surface and generally convex outersurface). In one embodiment, seal portion 16 has a generally rounded,convex face engaging surface for engaging face 22 of subject 12. In oneembodiment, the face engaging surface has a more flattened, convexconfiguration. Also, different regions of seal portion 16 around theperimeter of mask body 14 may have different cross-sectionalconfigurations. Various other seal portion configurations will becomeapparent to those skilled in the art.

In one embodiment, seal portion 16 is attached to mask body 14 at anattachment region 28, as shown in FIG. 1. Attachment region 28 may bealong the perimeter or edge of the mask body 14 and along a perimeter oredge of the seal portion 16, such that there is some overlap of therespective edges of the mask body 14 and the seal portion 16, as shown.Accordingly, there is some material of the mask body 14 that engageswith some material of seal portion 16, such that a layered connection isformed. Other embodiments are contemplated in which there is no overlap,such as by attaching mask body 14 and seal portion 16 with their edgesend to end (e.g., by an adhesive connection), and/or where mask body 14and seal portion 16 are formed as a single piece.

In one embodiment, mask body 14 and seal portion 16 are configured toengage face 22 of subject 12 in an engagement region 30 that extendsfrom between the chin 32 and lips 34, upwardly along region 30 onopposite sides of the mouth of subject 12, and across the nose 36 andover the bridge of the nose 36, as shown. In this embodiment, sealportion 16 is generally oblong or pear shaped, as shown in FIG. 1. Sealportion 16 accordingly includes an upper portion 38, a lower portion 40,and a transition portion 42. Upper portion 38, which may be configuredto engage the face 22 of subject 12 across the bridge of the nose 36,has a radius of curvature that is relatively smaller than the radius ofcurvature R2 of lower portion 40. Lower portion 40, with itscomparatively larger radius of curvature, may be configured to engagethe face 22 of subject 12 between chin 32 and lips 34. Transitionportion 42 extends generally from upper portion 38 to lower portion 40and engages the face 22 of subject 12 and beneath the eyes. Tofacilitate creating a sealed engagement with face 22 of subject 12,transition portion 42 of seal portion 16 has more material in itscross-section, and has a greater linear length (i.e., if seal portion 16were to be unrolled or straightened into a linear configuration) whenmeasured in a direction extending orthogonally away from mask body 14,than each of upper portion 38 and lower portion 40, so as to effectivelyblock gas within chamber 24 from reaching the eyes of subject 12.

While the embodiment of seal portion 16 and mask body 14 may be sized toenclose the mouth and nose 36 of subject, this is not intended to belimiting. In one embodiment, mask 10 may be configured to enclose fewerexternal orifices of the airway of subject 12 (e.g., only the nostrils,only one nostril, only the mouth, etc.). One of ordinary skill in theart will appreciate that the configuration of mask 10 may vary and isnot limited to a particular size or configuration, as subject 12 mayrange in age, size, and/or medical treatment required so as to requireappropriate selection from among a variety of different mask sizes andconfigurations.

On a side of the mask body 14 that is opposite from seal portion 16,mask body 14 forms an opening 44 for receipt of source connector 18.Through opening 44, a breathable substance is provided into chamber 24for inhalation by subject 12. Also, gas exhaled by subject 12 may beexhausted from chamber 24 to ambient atmosphere via opening 44. In oneembodiment, opening 44 is configured to connect with source connector18.

In one embodiment, source connector 18 comprises a conduit 46 that formsa gas flow path, when connected with mask body 14, from opening 44 to asource interface opening 48 formed in source connector 18. Sourceconnector 18 is configured to connect a source of a breathable substanceto the gas flow path between opening 44 of mask body 14 and sourceinterface opening 48 so that the breathable substance can be deliveredfrom source interface opening 48 to chamber 24 for inhalation by subject12. In one embodiment, source connector 18 is formed from a relativelyrigid material (e.g., rigid silicone resin). In one embodiment, sourceconnector 18 is formed from a less rigid material (e.g., flexiblesilicone). In one embodiment, conduit 46 of source connector 18 formedseparately from mask body 14, and is securely attached to mask body 14.For example, source connector 18 may be securely attached to opening 44formed in mask body 14 by a permanent snap fit, an adhesive, heatstaking, ultra-sonic welding, and/or otherwise secured to mask body 14.

In one embodiment, source connector 18 is configured to selectably andreleasably engage the source of the breathable substance. In oneembodiment, source connector 18 is configured to be permanently attachedto the source and/or to be formed integrally with the source. The sourceof the breathable substance may include one or more of metered doseinhaler, a pressurized metered dose inhaler, a static chamber incommunication with an inhaler, a nebulizer, a spacer, an aerosoldispenser, and/or other suitable sources of breathable substances. Itwill be appreciated that, in order to appropriately interface with maskbody 14 and the source of the breathable substance, source connector 18can be of various sizes, shapes, and configurations other than the onesillustrated in FIG. 1.

Exhaust valve 20 is disposed on source connector 18, and is configuredto exhaust gas exhaled from the enclosed one or more external orificesof subject 12 to ambient atmosphere. However, exhaust valve 20 isfurther configured to substantially seal the gas flow path formed withinsource connector 18 from inflows of ambient atmosphere. As such, exhaustvalve 20 is a one-way valve.

FIG. 2 illustrates how mask 10 can be removed from the source. In theembodiment illustrated in FIG. 2, the source is a spacer that isconnected to a metered dose inhaler. The metered dose inhaler isconfigured to dispense a breathable substance into the spacer, and thebreathable substance is received by source connector 18 (when connected)from the spacer/metered dose inhaler combination. In the embodimentillustrated in FIG. 2, the selectively removable attachment of sourceconnector 18 to the spacer is accomplished via a friction fit.

FIG. 2 shows a cross-sectional view of mask 10, in accordance with oneor more embodiments of the invention. In the view shown in FIG. 2, sealportion 16 has been engaged with face 22 of subject 12 to form chamber24 between the face 22 and mask body 14. During inhalation by subject12, air intermixed with the breathable substance is received intochamber 24 via source connector 18 and opening 44. During exhalation bysubject 12, the pressure within chamber 24 opens exhaust valve 20,thereby releasing exhaled gas from chamber 24 to ambient atmosphere.

In the embodiment shown in FIG. 2, exhaust valve 20 includes an exhaustopening 50 formed in conduit 46 and a valve member 52. The defaultposition of valve member 52 is covering exhaust opening 50 tosubstantially seal conduit 46 from inflows of gas at ambient atmosphere.In one embodiment, valve member 52 is biased into this default positionby one or more of a spring bias, a magnetic force, gravity, a resiliencyof the materials of valve member 52, and/or other forces. In oneembodiment, valve member 52 is only attached to source connector 18along an attached side 54. If the pressure within chamber 24 reaches apredetermined level, valve member 52 is actuated away from exhaustopening 50 to release gas within chamber 24 to atmosphere. In oneembodiment, to actuate away from exhaust opening 50, valve member 52pivots at or near attached side 54. The pivoting of valve member 52 ator near attached side 54 may be due to a hinge provided at or nearattached side 54. In one embodiment, to actuate away from exhaustopening 50, valve member 52 resiliently flexes away from exhaust opening50.

The disposition of exhaust valve 20 on source connector 18, rather thanon mask body 14, may provide one or more enhancements to thefunctionality of mask 10. For example, generally, mask body 14 is formedfrom a transparent or translucent material to enable a caregiver tovisually monitor the reception of treatment by subject 12. The caregivermay monitor, for instance, the enclosed one or more external orifices tofor indications as to the efficacy of the treatment being receivedand/or for indications that subject 12 is being ventilated adequatelyduring respiration. By way of non-limiting example, the caregiver maycheck to see if the mouth of subject 12 is open and/or if the nostrilsof subject 12 are flared during inspiration, indicating a certain amountof effort being expended in order to inhale. As another example, thecaregiver may monitor the color of lips 34 of subject 12, as lips thatbecome purple or blue may indicate that subject 12 is not beingadequately ventilated. By locating exhaust valve 20 on source connector18, the caregiver is provided with a substantially unimpeded view of themount and/or nose of subject 12 during treatment.

In one embodiment, the uncovering of exhaust opening 50 provides anindicator to the caregiver of exhalation by subject 12. In theembodiment illustrated in FIG. 2, pressure within chamber 24 resultingfrom exhalation by subject 12 causes valve member 52 to be actuated awayfrom exhaust opening 50 to uncover exhaust opening and exhaust exhaledgas to ambient atmosphere. As should be appreciated from theillustration provided in FIG. 2 and the description above, actuation ofvalve member 52 may include valve member 52 pivoting or resilientlybending at or near attached side 54. This pivoting or bending would beobservable for the caregiver and would provide a marker to the caregiverthat a breath has been taken by subject 12. The implementation of ahinge at or along attached side 54 may, in some instances, increase therange of motion of valve member 52, which enhances the visible markerprovided by valve 20 of exhalation by subject 12. For treatmentsadministered through mask 10 that are given for a predetermined numberof breaths (e.g., treatments from a metered dose inhaler, etc.),providing the caregiver with a mechanism for marking and/or countingbreaths will facilitate administration of treatment.

It will be appreciated that in embodiments in which the actuation ofvalve member 52 away from exhaust opening 50 provides a marker to thecaregiver that a breath has been taken by subject 12 there is a tensionbetween at least two design values of exhaust valve 20. The first designvalue is the sensitivity of the marker provided to the caregiver ofexhalation, and the second design value is the reduction of resistanceto exhaled gas associated with exhaust valve 20. In order to beadequately sensitive to exhalations, particularly for children, elderlyadults, and/or other subjects that are particularly weak, the openingsize of exhaust opening 50 may be reduced. This will increase thepressure within chamber 24 during exhalation, the flow rate of gasthrough exhaust opening 50, and the corresponding force applied by thegas to valve member, all of which will enhance the sensitivity of themarker to exhalation. However, the increase in pressure within chamber24 during exhalation caused by the increase in resistance of exhaustopening 20 caused by a reduction in the size of exhaust opening 50 maybe associated with one or more drawbacks. These drawbacks may include adiscomfort of subject 12 (particularly for stronger subjects) caused bythe increased pressure, back pressure, and/or resistance to exhalation,and/or other drawbacks.

FIG. 4 illustrates an embodiment of mask 10 in which the sensitivity ofthe marker of exhalation provided by exhaust valve 20 is enhanced whilereducing the resistance of exhaust valve 20 during exhalation forstronger subjects. In the embodiment, shown in FIG. 4, exhaust valve 20includes two separate exhaust openings formed in source connector 18, afirst exhaust opening 66 and a second exhaust opening 68, which arecovered by a first valve member 70 and a second valve member 72,respectively.

In one embodiment, the area of first exhaust opening 66 is larger thansecond exhaust opening 68. The outer perimeter of first valve member 70corresponds to the edge of first exhaust opening 66 such that firstvalve member 70 has a default position at which first valve member 70covers first exhaust opening 66 to block inflows of gas through firstexhaust opening 66 from ambient atmosphere into the chamber formed bymask body 14 and the face of the subject. Similarly, the outer perimeterof second valve member 72 corresponds to the edge of first exhaustopening 68 such that second valve member 72 has a default position atwhich second valve member 72 covers second exhaust opening 68 to blockinflows of gas from ambient atmosphere through second exhaust opening68. First valve member 70 and second valve member 72 are attached tosource connector at attached edges 74 and 76, respectively. First valvemember 70 and second valve member 72 are configured to pivot orresiliently bend at or near attached edges 74 and 76 to actuate awayfrom first exhaust opening 66 and second exhaust opening 68. In oneembodiment, one or both of first valve member 70 and second valve member72 are attached to exhaust valve 20 by a hinge disposed along attachedside 74 and/or attached side 76.

In one embodiment, at or above a first pressure within the chamberformed by mask body 14 and the face of the subject, first valve member70 is actuated away from first exhaust opening 58 to exhaust gas fromwithin the chamber to atmosphere, thereby providing a marker ofexhalation of the subject. At or above a second pressure that is greaterthan the first pressure, second valve member 72 is actuated away fromsecond exhaust opening 58 to exhaust gas from within the chamber toatmosphere, thereby reducing the resistance of exhaust valve 20 to gasflowing out of the chamber through exhaust valve 20. Alternativelyand/or additionally to providing a relative size differentials of firstexhaust opening 22 and second exhaust opening 68, the relative thicknessand/or weight of first valve member 70 and second valve member 72 may bedifferent in order to further tailor the pressure differential betweenthe first pressure and the second pressure, and/or to ensure that firstvalve member 70 provides an adequate marker for exhalalations.

In one embodiment, first valve member 70 and second valve member 72 areformed from separate pieces of material. In one embodiment, first valvemember 70 and second valve member 72 are formed from a single piece ofmaterial with a cross-member 77 providing an anchor that separates firstvalve member 70 from second valve member 72. Cross-member 77 is a rigidstructure that holds the piece of material forming valve members 70 and72 in place along attached edges 74 and 76.

It will be appreciated that the embodiments of exhaust valve 20 shown inFIG. 4 that enhances the sensitivity of the marker of exhalationprovided by exhaust valve 20 while reducing the resistance of exhaustvalve 20 during stronger and/or more voluminous exhalation are notintended to be limiting. The scope of the disclosure of this featureencompasses any embodiments of exhaust valve 20 in which a first portionone or more exhaust openings are uncovered to exhaust gas from withinthe chamber formed between mask body 14 and the face of a subject if thepressure within the chamber is greater than or equal to a first,relatively low pressure, and a second portion of the one or more exhaustopenings are uncovered to exhaust gas if the pressure within the chamberis greater than or equal to a second pressure that is higher than thefirst pressure. For example, a plurality of valve members may cover asingle exhaust opening. As another example, the valve members coveringthe one or more exhaust openings may or may not be flaps (e.g., attachedalong one edge). The number of valve members and/or exhaust openingsincluded in exhaust valve 20 may be greater than two. The exhaustopenings of exhaust valve 20 may be located separately from each (e.g.,not adjacent as shown in FIG. 4). Exhaust valve 20 may include one ormore exhaust openings formed on mask body 14, rather than on sourceconnector 18.

FIG. 5 illustrates a method 78 of isolating the airway of a subject fromatmosphere to facilitate delivery of a breathable substance. Theoperations of method 78 presented below are intended to be illustrative.In some embodiments, method 78 may be accomplished with one or moreadditional operations not described, and/or without one or more of theoperations discussed. Additionally, the order in which the operations ofmethod 78 are illustrated in FIG. 5 and described below is not intendedto be limiting. Although the operations of method 78 are described belowwith references to components of a mask that is the same as or similarto mask 10 (shown in FIGS. 1-4 and described above), this is notintended to be limiting. Method 78 may be implemented in a variety ofother contexts without departing from the scope of this disclosure.

At an operation 80, a chamber is formed that encloses one or moreexternal orifices of the airway of the subject. The chamber is formed inpart by the face of the subject. In one embodiment, operation 80 isperformed by a mask body that is the same as or similar to mask body 14(shown in FIGS. 1-4 and described above).

At an operation 82, a source of a breathable substance is placed incommunication with the chamber via a conduit. The conduit forms a gasflow path between a source interface opening configured to connect withthe source and a substance opening formed in the chamber. In oneembodiment, operation 82 is performed by a source connector that is thesame as or similar to source connector 18 (shown in FIGS. 1-4 anddescribed above).

At an operation 84, the breathable substance is delivered from thesource of the breathable substance to the chamber without permittinginflows from ambient atmosphere into the chamber and/or the conduit.This may include blocking inflows of gas at ambient atmosphere fromentering the chamber via one or more exhaust openings. The one or moreexhaust openings may include one or more exhaust openings formed in theconduit and/or in the chamber. In one embodiment, operation 84 isperformed by an exhaust valve that is similar to or the same as exhaustvalve 20 (shown in FIGS. 1-4 and described above).

At an operation 86, gas exhaled by the subject is exhausted to ambientatmosphere through the one or more exhaust openings. In one embodiment,operation 86 includes uncovering a first portion of the one or moreexhaust openings at or above a first pressure within the chamber and/oruncovering a second portion of the one or more exhaust openings at orabove a second pressure within the chamber that is greater than thefirst pressure. In one embodiment, operation 86 is performed by anexhaust valve that is the same as or similar to exhaust valve 20 (shownin FIGS. 1-4 and described above).

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. For example, it is to be understood thatthe present invention contemplates that, to the extent possible, one ormore features of any embodiment can be combined with one or morefeatures of any other embodiment.

1. A mask for substantially sealing the airway of a subject for deliveryof a breathable substance, the mask comprising: a mask body configuredto enclose one or more external orifices of the airway of a subject,wherein the mask body forms a substance opening through which abreathable substance can be communicated to the one or more externalorifices of the subject that are enclosed by the mask body; a sourceconnector disposed on the mask body, the source connector comprising aconduit that forms a gas flow path between the substance opening of themask body and a source interface opening formed in the source connector,wherein the source connector is configured to connect a source of thebreathable substance to the gas flow path between the substance openingof the mask body and the source interface opening; a mask seal portionattached to the mask body, the mask seal being configured to provide asubstantially sealed engagement between the face of the subject and themask body around the one or more external orifices of the airway of thesubject; and a one-way valve disposed on the source connector configuredto permit gas within the gas flow path formed by the source connector tobe exhausted to ambient atmosphere and to substantially seal the gasflow path from inflows of ambient atmosphere.
 2. The mask of claim 1,wherein the one-way valve forms a exhaust opening in the sourceconnector that, if left open, communicates the gas flow path formed bythe source connector with ambient atmosphere, wherein the one-way valvecomprises one or more valve members configured (i) to cover the exhaustopening during inhalation by the subject to substantially seal the gasflow path from inflows of ambient atmosphere, and (ii) to uncover theexhaust opening during exhalation by the subject to exhaust gas exhaledfrom the one or more external orifices of the subject to ambientatmosphere.
 3. The mask of claim 2, wherein the one or more valvemembers are configured to provide a visual indication of whether or notthe exhaust opening is covered.
 4. The mask of claim 3, wherein the oneor more valve members comprises a flap that is actuated away from theexhaust opening to uncover the exhaust opening, and wherein theactuation of the valve member away from the exhaust opening provides thevisual indication of whether or not the exhaust opening is covered. 5.The mask of claim 3, the one or more valve members are actuated awayfrom the exhaust opening to uncover the exhaust opening by the force ofgas exhaled from the one or more external orifices of the subject as theexhaled gas is exhausted to ambient atmosphere through the exhaustopening.
 6. The mask of claim 5, wherein the one or more valve memberscomprise a plurality of valve members, and wherein at least one of thevalve members is configured to be actuated away from the exhaust openingby a smaller amount of force than the other valve members.
 7. The maskof claim 1, wherein the mask body is formed at least in part from asubstantially transparent material such that a caregiver is providedwith a view of the one or more external orifices of the airway of thesubject that is substantially unimpeded by the one-way valve.
 8. A maskfor substantially sealing the airway of a subject for delivery of abreathable substance, the mask comprising: means for forming a chamberthat encloses one or more external orifices of the airway of a subject,wherein a portion of the chamber is formed by the face of the subject;means for placing a source of a breathable substance in communicationwith the chamber via a conduit forming a gas flow path between a sourceinterface opening and a substance opening formed in the chamber byconnecting the source of the breathable substance to the sourceinterface opening; means for delivering the breathable substance fromthe source of the breathable substance to the chamber through theconduit without permitting inflows from ambient atmosphere into theconduit; and means for exhausting gas exhaled by the subject to ambientatmosphere through an exhaust opening in the conduit.
 9. The mask ofclaim 8, wherein the means for delivering the breathable substance fromthe source of the breathable substance to the chamber through theconduit without permitting inflows from ambient atmosphere into theconduit comprises means for covering the exhaust opening with one ormore valve members, and wherein the means for exhausting gas exhaled bythe subject to ambient atmosphere through the exhaust opening in theconduit comprises means for actuating the one or more valve members awayfrom the exhaust opening to uncover the exhaust opening.
 10. The mask ofclaim 9, further comprising means for providing a visual indication ofwhether or not the exhaust opening is covered.
 11. The mask of claim 10,wherein the one or more valve members comprise a flap, and wherein theactuation of the flap away from the exhaust opening provides the visualindication of whether or not the exhaust opening is covered.
 12. Themask of claim 10, wherein the one or more valve members are actuatedaway from the exhaust opening to uncover the exhaust opening by theforce of gas exhaled from the one or more external orifices of thesubject as the exhaled gas is exhausted to ambient atmosphere throughthe exhaust opening.
 13. The mask of claim 12, wherein the one or morevalve members comprise a plurality of valve members, and wherein atleast one of the valve members is configured to be actuated away fromthe exhaust opening by a smaller amount of force than the other valvemembers.
 14. The mask of claim 1, wherein the chamber is formed at leastin part from a substantially transparent material such that a caregiveris provided with a view of the one or more external orifices of theairway of the subject that is substantially unimpeded by the exhaustopening and one or more valve members that cover the exhaust opening.15. A method of substantially sealing the airway of a subject fordelivery of a breathable substance, the method comprising: forming achamber that encloses one or more external orifices of the airway of asubject, wherein a portion of the chamber is formed by the face of thesubject; placing a source of a breathable substance in communicationwith the chamber via a conduit forming a gas flow path between a sourceinterface opening and a substance opening formed in the chamber byconnecting the source of the breathable substance to the sourceinterface opening; delivering the breathable substance from the sourceof the breathable substance to the chamber through the conduit withoutpermitting inflows from ambient atmosphere into the conduit; andexhausting gas exhaled by the subject to ambient atmosphere through anexhaust opening in the conduit.
 16. The method of claim 15, whereindelivering the breathable substance from the source of the breathablesubstance to the chamber through the conduit without permitting inflowsfrom ambient atmosphere into the conduit comprises covering the exhaustopening with one or more valve members, and wherein exhausting gasexhaled by the subject to ambient atmosphere through the exhaust openingin the conduit comprises actuating the one or more valve members awayfrom the exhaust opening to uncover the exhaust opening.
 17. The methodof claim 16, further comprising providing a visual indication of whetheror not the exhaust opening is covered.
 18. The method of claim 17,wherein the one or more valve members comprise a flap, and wherein theactuation of the flap away from the exhaust opening provides the visualindication of whether or not the exhaust opening is covered.
 19. Themethod of claim 17, wherein the one or more valve members are actuatedaway from the exhaust opening to uncover the exhaust opening by theforce of gas exhaled from the one or more external orifices of thesubject as the exhaled gas is exhausted to ambient atmosphere throughthe exhaust opening.
 20. The method of claim 19, wherein the one or morevalve members comprise a plurality of valve members, and wherein atleast one of the valve members is configured to be actuated away fromthe exhaust opening by a smaller amount of force than the other valvemembers.
 21. The method of claim 15, wherein the chamber is formed atleast in part from a substantially transparent material such that acaregiver is provided with a view of the one or more external orificesof the airway of the subject that is substantially unimpeded by theexhaust opening and one or more valve members that cover the exhaustopening.